This invention relates to stators and rotors for electric motors having reduced weight and improved corrosion resistance.
Conventional stators and rotors for electric motors are typically made from machined, cast or forged metals including steel. To provide corrosion resistance metal alloys are frequently used. In many instances it is important not only to improve the corrosion resistance but also to reduce the weight of the stators and rotors in an electric motor.
The Brown U.S. Pat. Nos. 4,729,160 and 4,930,201 disclose a rotor having a plurality of magnets bonded to a rotor hub and a composite sleeve disposed over the rotor hub and magnets. The Tassinario U.S. Pat. No. 4,879,485 discloses a permanent magnet rotor containing a stack of circular sheets of magnetic material mounted on a shaft and an array of permanent magnets adhesively bonded to the periphery of the stack of sheets, the magnets having inwardly inclined adjacent edges forming V-shaped openings. Carbon or glass fibers are wound through the V-shaped openings provided by the magnets to retain the magnets in place and a resin is applied over the threads in each opening to provide a continuous cylindrical surface. The El-Antably et al. U.S. Pat. No. 5,296,773 describes a rotor assembly consisting of a plurality of axial laminations alternately containing magnetic and non-magnetic material with an end cap at each axial end which engages stepped axial ends of the laminations, the outermost lamination on the rotor being a composite material with a carbon fiber center and a fiberglass outer layer. U.S. Pat. No. 4,433,261 to Nashiki, et al., discloses a rotor having a plurality of magnet sectors mounted on a shaft which are axially displaced with respect to each other and side plates of non-magnetic metal having recesses to receive the displaced magnet ends. The periphery of the rotor has a layer of non-magnetic fiber such as glass fiber, carbon fiber or the like, secured with a resin.
The Trago et al. U.S. Pat. No. 5,806,169 discloses an injection molded motor assembly including a stator assembled from a series of laminations having a plurality of teeth forming the stator poles and surrounded by windings which is then pressure filled with molten plastic to seal the assembly. U.S. Pat. No. 5,502,341 to Sato likewise discloses a stator assembled from laminated plates and having a resin-impregnated inner peripheral surface. In the Fukushi et al. U.S. Pat. No. 4,492,889, a stator assembly has a laminated stator core which receives stator coils and outer and inner cylinders enclosing the stator laminations and coils, along with end covers and a resin filling encapsulating the coils and laminations.